1 cup sour cream

2 1/2 teaspoons kosher salt

1/2 teaspoon freshly ground black pepper

1. Arrange a rack in the middle of the oven and heat the oven to 400 F. Coat a 9-by-13-inch or other 2 1/2-quart baking dish with 2 tablespoons unsalted butter.

2. Peel the potatoes. Cut with a sharp knife or mandolin into 1/8-inch thick rounds. Place in a large bowl and add enough cold water to cover. Grate 6 ounces dill havarti cheese and 2 ounces Parmesan cheese on the large holes of a box grater (keep them separate).

3. Finely grate 4 garlic cloves into a second large bowl. Finely grate the zest of 1 medium lemon into the bowl. Finely chop the following fresh herbs and add to the bowl: 2 tablespoons chives, 2 tablespoons dill, and 1 tablespoon parsley. Add 2 cups heavy cream, 1 cup sour cream, 2 1/2 teaspoons kosher salt and 1/2 teaspoon black pepper, and whisk to combine.

4. Drain the potatoes and pat dry with a kitchen towel. Add the potatoes and half of the havarti cheese into the cream mixture and toss to coat. Transfer the potatoes one handful at a time to the baking dish, arranging them into an even layer. Pour any remaining cream mixture over the potatoes. Tightly cover with aluminum foil.

5. Bake for 40 minutes. Uncover and sprinkle with the Parmesan and remaining havarti cheese. Bake uncovered until the potatoes are fork tender and the top is golden brown, about 30 minutes more. Let cool 10 minutes before serving.

Recipe notes: The gratin can be assembled the same day and refrigerated until ready to bake. Refrigerate leftovers in an airtight container up to four days.

(Grant Melton is a contributor to TheKitchn.com, a nationally known blog for people who love food and home cooking. Submit any comments or questions to editorial@thekitchn.com.)

©2021 Apartment Therapy. Distributed by Tribune Content Agency, LLC.